This summer’s conditions are clear to anyone living in Sonoma. The landscape is more gold than green, and the area’s first red-flag warning came in early June, followed by another over the 4th of July weekend.
Winter usually brings us much-needed moisture, and it did, at first. But the season ended dry, then spring arrived with record-breaking heat, which, in turn, depleted the Sierra snowpack. Now, the North Bay is officially “abnormally dry,” and we’re not even halfway through the summer.
Clearly, there is potential for an above-average fire season, but what’s harder to see is what’s happening underground. Drought doesn’t just parch the landscape; it can reshape a tree’s health for years.
Is There a Drought in California?
Sonoma’s not in a drought…yet.
The term “abnormally dry” is not just stating the obvious about our situation. The term refers to the first stage the U.S. Drought Monitor tracks and can indicate when a region is entering drought.
While we’re not there yet, drought is a specter on the horizon. In the meantime, heat stress on trees can affect your orchard.
Signs of Drought Stress in Fruit Trees
The recent high temperatures and wind have depleted the top layer of our soil of moisture. This, in turn, will impact your trees and fruit harvest.
Smaller fruit sizes: Summer heat and low moisture strain a tree’s energy. Instead of putting all its resources towards growing large, juicy produce, it diverts them to staying alive. Thus, the quality and size of summer crops like apples, pears, and stone fruits are reduced.
Sunscald: Seasonal damage is always a concern, but now the risk is higher. Depleted trees often can’t keep fruit properly shaded and cooled, and compromised bark is exposed to strong sunshine.
Leaf scorch and early drop: Fruit trees will shed their leaves to economize on energy and reduce water use. Keep an eye out for curling leaves and those with browning edges.
Wilting that doesn’t bounce back: A little afternoon droop that perks back up overnight is normal. Wilting that’s still there in the morning is the tree telling you it’s out of reserves.
The Long-Term Effects of Drought Stress in Fruit Trees
- Delayed damage: Trees largely rely on fine root hairs to pull water from the soil. When the earth around them is moisture-deficient, they’re the first thing to die off. Losing them costs the tree access to water and can trigger dieback in the branches above. However, the most worrisome aspect is that this type of damage often goes undetected for some time. An apple tree that looks like it made it through a droughty summer can show stunted growth and decline one, two, or even three years later. That unseen weakness can make it more susceptible to plant disease and a host of unwanted critters.
- Pests: Trees under duress are unable to expend energy to stand up to intruders. Your orchard’s trees become easier targets for wood borers and other fruit tree pests that wouldn’t normally be able to take hold.
Can Fruit Trees Recover from Heat Stress
If addressed quickly, your property’s orchard will recuperate. However, playing offense versus defense is always a better strategy. The best way to facilitate heat stress resistance and recovery is proactive fruit tree maintenance.
If nothing else, seasonal pruning is one of the most important things you can do to support your trees. Doing so helps them use energy efficiently and aids overall health.
When we’re operating under abnormally dry conditions and beyond, there are further steps you can take:
- Young trees: If you’ve recently planted fruit trees, they need water once a week for the first three years. This is especially important in times of deficient soil moisture.
- Mature trees: Established fruit trees can sometimes thrive with no additional water other than what their roots can find on their own. During dry or drought conditions, they need to be deeply watered once a week.
- Deep watering: Instead of frequent, shallow watering like a spray with a hose, go for saturation with minimal water waste. Focus on the outer edge of your tree’s canopy and use a soaker hose or drip irrigation. This prevents runoff water waste and is more effective at allowing the water to soak in. After a few hours of watering, check the soil moisture.
- Mulch: In these circumstances, water evaporates in an instant. Insulating your tree’s root zone helps to retain moisture and keep the ground cooler. Just be careful to leave a ring around the trunk bare to protect against pests and disease.
Protect trunks: If you have young trees or those exposed to particularly strong sun, we suggest applying whitewash to their trunks. Like zinc on your nose, it provides sun protection and can significantly reduce the surface temperature.
Drought Tolerant Fruit Trees
- Figs: Once established, these fruit trees are survivors. Black Mission and Brown Turkey do particularly well in our climate.
- Pomegranates: Can survive long waterless spells, however, a little extra does help fruit quality and size.
- Olives: An excellent, low-water choice, olives can’t be plucked off a tree and eaten raw. But they are great cured and are lovely additions to a property.
- Persimmons: Both Fuyu and Hachiya can handle parched periods and taste delicious.
- Jujubes: Wonderfully drought-tolerant, these apple-like fruits dehydrate into date consistency right on the branch.
Apples and Pears: Once mature, these classic fruit trees can survive dry periods. That said, if you’d like quality fruit, they need water.
Although they are good for the environment, drought-tolerant trees will not protect your property from wildfire. While we all hope none occur, it is a Sonoma inevitability. By taking steps to prepare fruit trees for fire season, we’re protecting our homes and our firefighters.
Almonds and California Drought
You may have heard that a single almond tree is thirstier than other varieties. That is debatable, depending on the fruit or nut-tree variety. The problem is that, as California’s number one agricultural export, over 1.3 million acres are devoted to growing them. The cumulative water demand for all those almond trees outstrips that of other crops.
Looking Ahead
Drought isn’t the only extreme Sonoma trees have to deal with. Just a few months from now, we’ll hopefully swing the other direction. Instead of heat and sun, we’ll be encountering atmospheric rivers and bomb cyclones dumping heavy rain in short bursts, which cause flooding, waterlogged roots, and mold issues.
However, while we wait for the next atmospheric shift, if you have questions or need a hand with your Sonoma fruit trees, we can help. Contact us for a consultation.